Revised the Asian Independent 16 oct to 31 oct 2019

www.theasianindependent.co.uk
New Delhi-Researchers
have discovered two strains of
'plastic-eating' bacteria from
the wetlands of Greater Noida,
an advance that may lead to
eco-friendly alternative cleanup
methods for plastic waste
worldwide. The bacterial
strains discovered by
researchers at Shiv Nadar
University in Greater Noida,
Uttar Pradesh, have the potential
to decompose polystyrene -
- a key component in Single-
Use Plastic (SUP) items such as
disposable cups, cutlery, toys,
packaging materials etc. The
bacterial species namely
Exiguobacterium sibiricum
strain DR11 and
Exiguobacterium undae strain
DR14 were isolated from the
wetlands adjoining the university.
Polystyrene is quite resistant
to degradation due to its
high molecular weight and long
chain polymer structure. This is
the reason for their persistence
in the environment, according
to the study published in the
journal Royal Society of
Chemistry (RSC) Advances.
The exponential production
and consumption of polystyrene
in various sectors has
presented a great environment
risk and raised the problem of
waste management, the
researchers noted. "Wetlands
are one of the richest habitats of
microbial diversity but are relatively
unexplored. Hence, these
TECH
'Plastic-eating' bacteria discovered
from wetlands of Greater Noida
ecosystems are ideal grounds
for isolating bacteria with
novel biotechnological applications,"
said Priyadarshini who
discovered the bacteria strains
along with her team at the
Department of Life Sciences,
School of Natural Sciences.
According to industry estimates,
India consumes about
16.5 million metric tonnes of
plastic annually.
The All India Plastic
Manufacturers Association
(AIPMA) estimates that the
plastic industry produces about
14 million metric tonnes of
polystyrene, which is nonbiodegradable.
This effects both terrestrial
and marine life, e.g. a plastic
fork can take up to 450 years
or more to decompose, the
researchers noted.
In the universe of plastic
items used daily, SUP constitutes
about a fifth in volume,
they said.
The finding assumes significance
in India given the recent
announcement by the Prime
Minister to eliminate SUP by
2022. The research team identified
that upon coming into contact
with the plastic (polystyrene),
the two isolated bacteria
strains use it as a carbon
source, and create biofilms.
This alters the physical
properties of polystyrene, and
initiates a process of natural
degradation with the release of
hydrolysing enzymes to break
the polymer chains.
"Biodegradation is a process by
which microbial organisms --
mainly bacteria and fungi --
transform or degrade chemicals
introduced into the environment,"
Priyadarshini said. The
team is currently trying to evaluate
the metabolic processes of
these strains for utilisation in
the environmental bioremediation.
"What started as a scientific
exploration of the wetland in
our campus has led to this significant
discovery of plasticeating
bacteria," said
Rupamanjari Ghosh, Vice-
Chancellor, Shiv Nadar
University. "This is a dream
solution of breaking plastic in a
natural process and making it
biodegradable," Ghosh said.
"We started out by just
16-10-2019 to 31-10-2019
exploring the area to get a sense
of bacterial species prevalent in
these areas, but ended up isolating
numerous bacterial species
with unique and useful properties,"
added Priyadarshini.
With new bacterial species
being discovered with plastic
biodegradation ability, she
noted that novel enzymes and
new potential metabolic pathways
can be discovered which
could help in bioremediation in
future.
The researchers noted that
both Exiguobacterium strains
19
were able to establish biofilms
on polystyrenes surfaces.
Biofilms are an assemblage
of bacterial cells, which grow
as communities, reaching to
very high cell densities.
This leads to more targeted
and localised action of polymer
degrading enzymes, the
researchers said. "Polystyrene
is quite recalcitrant to degradation
and requires some form of
pre-treatment like chemical,
thermal, photo-oxidation etc
prior to biodegradation," said
Priyadarshini. Both DR11 and
DR14 strains were able to not
only form biofilm on non-treated
polystyrene, but were also
found capable of degrading
unmodified plastic, researchers
said. "Human dependence on
plastic material has increased
substantially over the years,
which has led to huge amount
of plastic accumulation in the
environment leading to adverse
effects on the ecosystem,"
Priyadarshini said.
She noted that more sustainable
methods for plastic degradation
are required.
The researchers note that the
use of both indigenous and
genetically modified bacteria
could lead to eco-friendly alternative
clean-up methods for
plastic waste. Further research
should be directed towards
making these process faster,
sustainable and cost-effective,
they said.